Tag: orensen 3

Declines in AN were largely due to non-stomatal (diffusional and metabolic) limitations

Assessing stomatal and non-stomatal limitations to carbon assimilation under progressive drought in peanut (Arachis hypogaea L.)

Pilon C., Snider J. L., Sobolev V., Chastain D. R., Sorensen R. B., Meeks C. D., Massa A. N., Walk T., Singh B., Earl H. J. (2018)

Cristiane Pilon 1, John L Snider 2, Victor Sobolev 3, Daryl R Chastain 4, Ronald B Sorensen 3, Calvin D Meeks 5, Alicia N Massa 3, Travis Walk 3, Bhupinder Singh 4, Hugh J Earl 6

  • 1Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA, 31794, United States of America. Electronic address: cpilon@uga.edu.
  • 2Department of Crop and Soil Sciences, University of Georgia, 115 Coastal Way, Tifton, GA, 31794, United States of America.
  • 3USDA, Agricultural Research Service, National Peanut Research Laboratory, 1011 Forrester Drive, Dawson, GA, 39842, United States of America.
  • 4Delta Research and Extension Center, Mississippi State University, PO Box 197, Stoneville, MS, 38776, United States of America.
  • 5Fisher Delta Center, University of Missouri, 147 State Highway T, Portageville, MO 63873, United States of America.
  • 6Department of Plant Agriculture, University of Guelph, 50 Stone Road E., Guelph, Ontario, N1G 2W1, Canada.

J Plant Physiol. 231: 124-134 – doi: 10.1016/j.jplph.2018.09.007 – Epub 2018 Sep 20 – PMID: 30261481 –

https://pubmed.ncbi.nlm.nih.gov/30261481/

Abstract

Drought is known to limit carbon assimilation in plants. However, it has been debated whether photosynthesis is primarily inhibited by stomatal or non-stomatal factors. This research assessed the underlying limitations to photosynthesis in peanuts (Arachis hypogaea L.) grown under progressive drought. Specifically, field-grown peanut plants were exposed to either well-watered or drought-stressed conditions during flowering. Measurements included survey measurements of gas exchange, chlorophyll fluorescence, PSII thermotolerance, pigment content, and rapid A-Ci response (RACiR) assessments. Drought significantly decreased stomatal conductance with consequent declines in photosynthesis (AN), actual quantum yield of PSII, and electron transport rate (ETR). Pigment contents were variable and depended on stress severity. Stomatal closure on stressed plants resulted in higher leaf temperatures, but Fv/Fm and PSII thermotolerance were only slightly affected by drought. A strong, hyperbolic relationship was observed between stomatal conductance, AN, and ETR. However, when RACiR analysis was conducted, drought significantly decreased AN at Ci values comparable to drought-stressed plants, indicating non-stomatal limitations to AN. The maximum rate of carboxylation and maximum electron transport rate were severely limited by drought, and chloroplast CO2 concentration (CC) declined substantially under drought along with a comparable increase in partitioning of electron flow to photorespiration. Thus, while stomatal conductance may be a viable reference indicator of water deficit stress in peanut, we conclude that declines in AN were largely due to non-stomatal (diffusional and metabolic) limitations. Additionally, this is the first study to apply the rapid A-Ci response method to peanut, with comparable results to traditional A-Ci methods.